The field of the invention is splice and connector closures for fiber optic cables.
The size, shape, and composition of optical fibers render such fibers vulnerable to breakage or microbending due to physical tension or compression or the freezing and thawing of water. For these reasons, splices and connections of optical fibers are usually housed in secure splice closures.
Prior practice in design of such closures is to provide an area in the end caps of the closure through which craftspersons may drill a hole for cable insertion. A bracket is also provided within the enclosures having one or more fixed clamps. The craftsperson inserts the cable through a drilled hole and secures any rod-like cable strength member to a clamp. Prior art clamps consist of a plate which may be clamped to the bracket by a nut, holding the rod-like cable strength member therebetween. The rod-like strength member is prevented from pistoning into the actual splice area only by friction arising from the normal clamping force. Any fibrous cable tensile strength members, such as aramid fibers, cannot resist such pistoning out of the cable as this would be a compressive force, not a tensile force, with respect to the aramid fibers, even if the aramid fibers are also secured in the enclosure. A separate clamp around the outer sheath may prevent sheath movement into or out of the cable, but, again, does not prevent pistoning of a rod-like cable strength member.
A further difficulty with the fixed clamps is that it is difficult to line up the drill hole perfectly with the clamp. As a result, bending of the rod-like cable strength member is observed between the end cap and the clamp. Such bending seriously reduces the ability of the rod-like cable strength member to withstand compressive forces, which can lead to breakage of the rod-like cable strength member.